Displacement volume device



Oct. 11, 1938. E. Ef'HEwlTT DISPLAQEMENT VOLUME DEVICE ,Filed July s1, 1937 n @n NQ A.

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wm f S f l n Hl HW WNHHI l@ I I .Hill I IIIII www II/.V|!.lz||-r l! ...IHMHJPWT I .M www N@ Q n N mm IMJIIF W m Patented Oct. 1l, 1 938 UNITED STA-TES DISPLACEMENT `VOLUIME DEVICE Ellis E. Hewitt, Edgewood, Pa., assig'nor to The Westinghouse Air .Brake Company, Wilmerding, I ia., a corporation of Pennsylvania Application July 31, 1937, Serial No. 156,693

This invention relates to a vehicle fluid pressure brake equipmentand more particularly to an improved displacement reservoir or volume device for use in brake equipments of the type b employed on locomotives, or in which brake application means is provided which is operated on the supplyof fluid under pressure to an application chamber to effect the supply of fluid under pressure to a brake cylinder to produce an application of the brakes.

In certain types of brake equipment, such as the brake equipment employed on locomotives, there are provided equalizing valve devices which are similar to the usual triple valve devices emvfrom a pressure chamber corresponding to the usual auxiliary reservoir to an application chamber, instead of directly to the brake cylinder. An application piston subject to the opposing pressures of the fluid in the application chamber and of the fluid in a brake cylinder then operates to supply fluid under pressure to the brake cylinder from a reservoir, which may be the main reservoir on a locomotive.

When the brake cylinder piston of the usual type of brake equipment is moved in the bore in the brake cylinder from its release lposition towards the application position by fluid supplied to the brake cylinder by operation of a triple valve device, a certain amount of fluid is required to ll the space created by movement o f the piston. The space must be lled with fluid at atmospheric pressure before any eiective pressure is exerted on the brake cylinder piston to produce an application of the brakes.

In a brake equipment employing an application piston subject to the pressure oi' the fluid in an application chamber, the range of movement of the application piston is relatively small with the result that correspondingly little space is created by movement of the piston, and little fluid is required to nll the space so created.

Accordingly on the supply of iluid under pressure from the pressure chamber to the application chamber, when the pressure of the iluid in the pressure chamber is reduced by ow to the application chamber to the pressure to which brake pipe pressure is reduced in eil'ectingan appiication of the brakes, a higher pressure is de- 50 veloped in the application chamber than is de- .velopedin a brake cylinder on'the'supply of iiuid undervpressure thereto from an auxiliary reservoir'by the -usual triple valve device-on a corresponding reduction in'brake pipe pressure.' This higher application chamber pressure will` result ployed on cars, and arevada-pted to supply iluid 8 Claims. (Cl. 303-1) in the development of a higher pressure in abrake cylinder, such as the brake cylinder on a locomotive, which is supplied with fluid by operation of 'the application piston than in abrake cylinder on a car in the train hauled by the loco- -motive and which is supplied by a triple valve device. This produces different degrees of braking on vehicles equipped with diierent kinds of brake equipment, and causes different rates of retardation of the vehicles with accompanying objectionable slack action ina train composed of such vehicles.

It has heretofore been proposed to provide a piston movable on the supply of uid under pressu're to the chamber at a face thereof to provide aV volume corresponding to that created bymovement of a brake cylinder piston in a brake cylinder. 0n the supply of uid by the equalizing valve device fluid is supplied this chamber as well as'to the application chamber, so that the pressure developed in the application chamber builds up at the same rate as the pressure in a brake cylinder increases-on the supply of fluid thereto"V from an auxiliary reservoir. yA brake equipment of this type is shown in U.v S. Patent No. 1,451,440,A issued April 10, 1923 to Clyde C. Farmer.

It is an object of this invention to provide an improved displacement volume device or reservoir adapted for use in a brake equipment of the type described.

A further object of this invention is to provide an improved displacement volume' device employing a flexible diaphragm instead of a piston.

Another object of the invention is to provide 4 an improved displacement volume device of the type described in which the diaphragm employed therein is supported over substantially its entire area when the diaphragm is moved from its normal position by fluid under pressure in the chamber at the face thereof. Y

A further object of the invention is to provide an improved displacement volume device of the type described in which the'possibility of leakvage of uid under pressure therefrom is substantially eliminated.

Another object of the invention is to provide an improved displacement volume device of the type described which is adapted to be formed integralwith a reservoir employed in the associated iluid pressure brake equipment.

A further object of the invention is to provide an improved displacement volume device ofthe type described which is simple and rugged in construction.

Other objects of the invention and features of drawing.

f aisaosa position in which it is shown in Fig. 2 ofthe As a result of this movement of the diaphragm I space is created between the diaphragm I and the member 2, and the various parts o1' the device are proportioned so that the volume of this space is the equivalent of that created by movement of the piston of a brake cylinder from its release position to its application position.

After movementof the diaphragm I into engagement with the face of the member 3 further movement thereof is prevented, and on the continued supply of fluid under pressure to the pipe 26 there is .an increase in the pressure of -the uid in the chamber between the diaphragm I and the member 2, while there is a corresponding increase in the pressure of the uid in the application chamber which causes the application piston to move to a position to supplyv iluid Aunder pressure to the brake cylinder'.

0n an increase in the pressure of the fluid in the chamber between the diaphragm I and the member 2, the diaphragm I is pressed against the face of the member 3 which serves as a support for the diaphragm I, and prevents the diaphragm from being injured or overstressed upon an increase in the pressure of the iluid in the chamber at the face thereof'to a relativelyhigh value.

As the diaphragm is supported throughout substantially its entire area during the time it is subject to `iiuid under pressure, the diaphragm may be made relatively thin and iiexible so that it will move in response to a small increase in Athe pressure of the uid at the face thereof, and

member 3 is substantially the same in depth and cross section as the cavity in the face of the member 2, the central portion of the diaphragm I, which is oii'set and proportioned to t the cavity in the member 2, will extend into and ll the cavity in the face of the member 3 without harmful stretching or deformation of `the diaphragm.

0n the release of the brakes following an application, the equalizng valve device operates in the usual manner to release fluid under pressure from the pipe 26, thereby reducing the pressure of the uid in the chamber between the diaphragm I andthe member 2, while on this reduction in the pressure of the fluid in this chamber to a relatively small value, the spring- III pulls the diaphragm I away from the face of the member 3 and into engagement with the face of the member 2;"vwhile the convolutions of'the spring I0 nest within each other substantially as shown. in Figfl of the drawing. On the return of thediaphragm I to the position in which it is shown in Fig. 1, the space between the diaphragm I and 'the member 2 is reduced to a negligible volume.

to thereby prevent-objectionable pressure changes in this chamber. i

It will be seen that the displacement volume device provided by this invention is of simple construction and is adapted to be associated with a, sure, said diaphragm being moved into engageu reservoir employed ina iiuid pressure brake apparatus.

While one embodiment -of the invention has been illustrated and described in detail, it should be understood that theinvention is not limited to these details of construction, and that numerous changes and modications may be made without departing from the scope oi.' the following claims.

Having now described my invention, what I claimas new and desire to secure by Letters Patent, is:

l. In a device of the class described, in combination, a rigid member having a concave face thereon surrounded by an annular flange, a flexible diaphragm having its peripheral portion secured against said ange, said diaphragm and ,-said member cooperating to form aA chamber adapted to contain uid under pressure, a communication through which iluid under pressure may be supplied to and released from said chamber, and yielding means exerting force on the diaphragm tending to move said diaphragm towards the face of said member to reduce the volume of said chamber to a minimum, said yielding means comprising a spring mounted in said chamber 'and having one end secured to said member and having its other end secured to said diaphragm.

2. In a device of the class described, in combination, a rigid member having a concave face thereon surrounded by an annular ange, a ilexible diaphragm having its peripheral portion secured against said ilange, said diaphragm and said member cooperating to form a chamber adapted to contain fluid under pressure, a communication through which fluid under pressure may be suppliedto and released from said chamber, and yielding means exerting force on the dia-y phragm tending to move said diaphragm towards the face of said member to reduce the volume of said chamberto a minimum, said yielding means comprising a spiral spring mounted in said'chamber and having its convolutions arranged to nest within each other, the large end of said spiral spring being secured to said member and the small end of said spiral spring being secured to vsaid diaphragm substantially centrally thereof.

3. In a device of the class described', in combination, a rigid member having a concave face thereon surrounded-by an annular ilange, a ilexible diaphragm having its peripheral portion secured against said ange, said diaphragm and said member cooperating to form a chamber adapted to contain iiuid under pressure, said member having a circular recess substantially centrally of said concave face, a spiral spring mounted in said recess, said spring having its convolutions arranged to nest within each other and having its small end secured to said diaphragm substantially centrally thereof, a ring secured to said member and overlying a portion of the largest convolution of said spring to seand a communication through which fluid under pressure may be supplied to and released from said chamber. v

4. In a device of the class described, in combination, apair of rigid members having similar cavities in the vconfronting faces thereof, each of said members having an annular ange surrounding the cavity therein, a ilexible diaphragm having its peripheral Iportion clamped between the flanges on said members, said diaphragm cooperating with one of said members to form a chamber adapted to contain fluid under presl H H Mmmm 4 alemana ment with and being supported by the other of said members on the supply of uid. under pressure to said chamber, a communication through which fluid under pressure ma? be supplied to and released from said chamber, and yielding means exerting force on said diaphragm tending to move said diaphragm towards the face of said rst named member.

5. In a device of the-class described, in combie nation, a pair of rigid members having similar v cavities' in the confronting faces thereof, each of said members having an annular enge surrounding the cavity therein, a' ilexible dia` phragm having its peripheral `portionclamped between the anges on said members, said diaphragm cooperating with one of said members to form a chamber adapted vto contain iluid under ,f sure, said diaphragm bingmoved -into-engagey 4d ment with and being supported'v by the other of 6. In a device of the'class described, in com bination, a pair of rigid members-having similar .cavities in the confronting racesthe'reof, each of said members having an annular ange` surrounding the cavity therein, a ilex'ible, diaphragm lhaving its perlpherai v`portion clamped l vbetween the flanges en said members; said diaphragm cof operating with one .of said members' to form a chamber adapted to contain uid vunder pressaid members on the supply of Lfluid under pressure to said chamber, a communication through which iluidunder pressure may be supplied to and released from said chamber, *and yielding means exerting foree on saiddiaphragm tending to move said diaphragm towards the tace of said'firstvnamed member, said yielding means comprising a spiral spring mounted in said chamber. said spring having its convolntion secured to said rst named member and having its smallest convolution secured to said diaphragm substantially eentrallf.r thereof.

7. In a device of the class described, in combination, a pair of rigid members having similar cavities in the confronting faces thereof, each of said members having an annular ange snrroun-ing the cavity therein, a flexible diaphragm having its peripheral portion clamped between the flanges on said members, said diaphragm cooperating with one of said members to form a chamber adapted to contain fluid under pressure. said diaphragm being moved into engagement with and being supported by the other of said members on the supply of uid under pressure to said chamber, a communication through which uid under pressure may be supplied to and released from said chamber, yielding means exerting force on said diaphragm tending to move said vdiaphragm towards the face ot said irst named member, and a breather passage through which iluid under pressure mayiiow between the atmosphere and the area between the diaphragm and the yother of said members.

8. In a device of the class described, in combination, a pair oi rigid members having similar cavities in the confronting faces thereof, each of said members having an annuler` flange surrounding the cavity therein, a flexible diaphragm having its peripheral portion .clamped between the flanges on said members, said diaphragm cochamber adapted to contain tluid'under pressure, said diaphragm being moved into engagement withand being supported by the other of said members on the supply'of fluid under pressure to said chamber, a communication through which uid under pressure may ee supplied to and released from said chamber, yielding means exerting.force on said diaphragm tending to move said diaphragm towards the face of said iirst named member, said yielding means comoperating with one of said members to form a prising a spring mounted in said chamber and 

